With the rapid popularization of electronic documents, electronic documents gradually hold a more and more important position in many aspects of human life. Additionally, many electronic documents are very large at present. In this situation, a user can hardly find out a document content of his (her) interest merely through the document's catalogue and index. Although current Internet applications contain summary information and structural information for some documents, a user cannot grasp the summary information and structural information of a document in a short time, let alone rapidly find paragraphs of his (her) desired content out of a document having, for example, dozens of or even as many as hundreds of pages.
Hence, a scheme called “annotation” or “tagging” has emerged in applications for electronic documents. In this solution, a user can, upon reading of a specific content of a document, annotate the content using a succinct or general phrase as a tag. This procedure is usually called “annotation” or “tagging,” wherein a tag is a brief semantic description defined by a user for document content. For example, upon reading of document content about commercial housing price, a user tags the document content using a tag “house price.” When other user reads the document content, the tag annotated by a previous user for this document content can be displayed at the same time. Since tags have manual generalization results made by previous users for document content, tagging has become a very popular method which makes users to remark, collect and organize concerned electronic documents. There are currently the following two main manners of providing tagging service: providing tagging by a network service provider which provides a document content, and providing tagging by a network service provider which provides tagging service specially. However, each of the manners is a combination of a user's mental labor and manual action: first, reading a document, generalizing the document's content, and offering a phrase which generalizes the document's meaning, as a tag; then, manually associating the tag with a specific position of the document via a user interface provided by a service provider.
In view of this, there exists a need for a method for tagging a document, the method that can automatically determine where to tag the document, prompt to a user tags which are respectively suitable for other portions of the current document, and automatically tag the whole document.